The present invention relates to a pneumatic feeder dispenser for bulk materials arranged to progressively dispense measured amounts of bulk materials such as mortar, sand, gravel and particularly prepared cement employed in pressure spraying and injection forming processes.
Feeders of such materials have been known. For example, in Swiss Patent No. 432,360 a feeder is disclosed in which a body is provided with a plurality of chambers uniformly spaced about its periphery. Each of the chambers is open at both ends and arranged to run parallel to the rotational axis of the body. One of the front ends of the body is covered by a housing in which a material delivery slot is provided on one side and an inlet slot is provided on the other side. An analogous housing having a material outlet aligned with the air inlet slot aperture is provided to cover the other frontal end of the body. The material to be transported arrives from a bunker or a similar delivery device into the delivery slot in the upper housing cover and passes through said slot progressively into each of the chambers of the rotor body which body indexes at timed intervals. The rotor body indexes continuously at a speed of for instance ten revolutions per minute and the feed and speed of rotation are matched to one another in such a manner that the chambers become sequentially filled with the bulk material to be transported. The air inlet and material outlet are normally offset by 180.degree. from the delivery slot so that as the rotor indexes, pressurized air is forced into the air inlet forcing the material in the aligned chamber out the outlet opening.
A similarly constructed and operational compressed air conveyor device is disclosed in German Patent No. 485,983.
In practice, the bulk material feeders of the prior art present considerable difficulties when they are required to forward moist material. In operation such moist material becomes deposited inside the chambers of the rotor body in fine particles which builds up in increasing layers upon the chamber walls. Ultimately this decreases the capacity of each chamber and, finally, results in the chambers becoming incapable at all of transporting material. In order to maintain the said feeder in operative condition, it has become necessary to cleanse each chamber at least four times during every working shift. This is extremely laborious and costly, and a great loss of productivity and power is caused thereby. Such repeated interruption of operation for cleansing, requires the use of a second feeder inorder to ensure continuous throughput.
Another arrangement proposed in this field was disclosed in German Published Patent Application Number DAS 1,148,727. Such an arrangement comprises a housing within which a rotatable pocketed wheel is located. An exchangeable closing ring is located between the bottom of the wheel and of the housing, which can be replaced when clogged.
However, this does not satisfactorily meet the problem arising from the choking of the passages in the rotor so that a great deal of cleaning must still be made in order to maintain the device in operative condition.
It is therefore an object of the present invention to provide a peneumatic feeder-dispenser of the above type which overcomes the drawbacks and disadvantages of the known constructions.
Accordingly, it is another object of the present invention to provide a bulk material pneumatic feeder of the above type whose maintenance requirements are reduced to a minimum and which ensures a permanent continuous operation with little or no interruption in normal working patterns for cleansing.
It is still another object of the present invention to provide a bulk material pneumatic feeder comprising a rotor having regularly distributed over its periphery a plurality of chambers adapted to progressively receive and dispense the bulk material and wherein said material is prevented from forming sediments on the internal surfaces thereof.
It is a further object of the present invention to provide a bulk material pneumatic feeder of the type specified in which the bulk material sedimentation is prevented by an elastic rubber material lining covering at least in part the internal surfaces of the chambers.